Semiconductor device

1. A semiconductor device comprising: a semiconductor layer; a drift region of a first conductivity type provided in the semiconductor layer; a body region of a second conductivity type provided on the drift region in the semiconductor layer; a trench extending from a surface of the body region in the semiconductor layer with its bottom located in the drift region; a gate insulation film provided on an interior surface of the trench; a gate electrode provided in the trench with the intervention of the gate insulation film; a source region of the first conductivity type provided in a surface layer portion of the body region; a first impurity region of the second conductivity type provided around the bottom of the trench in spaced relation from the body region; and a second impurity region of the second conductivity type provided on a lateral side of the body region in the semiconductor layer, the second impurity region being isolated from the body region and electrically connected to the first impurity region.

2. The semiconductor device according to claim 1 , wherein the second impurity region extends from a surface of the semiconductor layer to a depth such as to reach the first impurity region.

3. The semiconductor device according to claim 1 , wherein the second impurity region has the same depth as the body region, the semiconductor device further comprising a buried impurity region of the second conductivity type provided below the second impurity region and connected to the first impurity region and the second impurity region.

4. The semiconductor device according to claim 1 , wherein the second impurity region is looped so as to surround the body region.

5. The semiconductor device according to claim 1 , wherein the trench includes a plurality of parallel portions which extend parallel to each other in a predetermined direction, and a connection portion which extends perpendicularly to the predetermined direction and connects one-end portions of the respective parallel portions.

6. The semiconductor device according to claim 5 , further comprising: a plug connected to a surface of the second impurity region; and an interconnection connected to the plug.

7. The semiconductor device according to claim 6 , wherein the plug includes a plurality of plugs arranged in spaced relation in a direction in which the connection portion extends, and the interconnection is connected commonly to the plurality of plugs.

8. The semiconductor device according to claim 6 , further comprising a contact region provided in a surface layer portion of the second impurity region and having a higher impurity concentration than the second impurity region.

9. The semiconductor device according to claim 8 , wherein the second impurity region is looped so as to surround the body region.

10. The semiconductor device according to claim 5 , further comprising a body contact region provided in the surface layer portion of the body region as extending thicknesswise through the source region and having a higher impurity concentration than the body region.

11. The semiconductor device according to claim 10 , wherein the body contact region includes a plurality of body contact regions arranged in spaced relation in a direction in which the parallel portions extend.

12. The semiconductor device according to claim 11 , further comprising: a plurality of source plugs provided in association with the respective body contact regions and each connected to the corresponding body contact region and a part of the source region around the body contact region; and a source interconnection connected commonly to the plurality of source plugs.